Efforts have been made to provide sturdy and relatively low cost suspensions for utility vehicles that frequently are driven on rugged and uneven terrain. Some of these utility vehicles have a drive train, including an engine and attached gear box, axle and differential, mounted on a sub-frame. Their suspension systems include a first pair of connections between the drive train sub-frame and the main frame of the vehicle through springs at the rear axle of the vehicle. A third connection between the drive train sub-frame and main frame may permit the rear axle, and the drive train sub-frame, to pivot with respect to the main frame. Examples of such connections are shown in U.S. Pat. Nos. 810,379; 2,001,029; 2,756,834; 2,836,254; 2,966,951; and 4,821,827.
This invention addresses two problems that may be found with the third connection between the drive train sub-frame and main frame. First, if the third connection involves direct engagement between the drive train sub-frame and the main frame, vibrations may be transferred from the drive train sub-frame to the main frame. Second, if the drive train sub-frame and main frame are not engaged directly together, the vehicle may not be safely shut down and stopped if the spring connections break at the other end of the drive train sub-frame.
Thus, an improved connection is needed between a drive train sub-frame and main frame that permits the rear axle and drive train sub-frame to pivot, that reduces or minimizes the transfer of vibration from the drive train sub-frame to the main frame, and that constrains the drive train sub-frame from coming loose if one or both of the spring connections between the sub-frame and main frame are broken.